1. Field of the Invention
The present invention relates to a simply constituted electronic apparatus that can definitely output data after a predetermined length of time from a time when an inputted data processing is started, even if data processing time of the input data varies with the contents of data.
2. Description of the Related Art
Conventionally, various electronic apparatus using microprocessors are publicly known. For example, the device proposed in Japanese Patent Laid-open Publication No. 1982-150046 is known. The device is so constituted that a timer, a timer control circuit or the like is connected to a microprocessor and the microprocessor can be executed together with a user program and a debugging control program correctly. In addition, in Japanese Patent Laid-open Publication No. 1982-203161, the device is so constituted that a shift register, a counter or the like is connected to the microprocessor and the operating conditions of the microprocessor can be monitored using a small number of external pins.
In a conventional device, it is basically considered that simple circuits such as a timer and a shift register are connected to the microprocessor, and the device can be operated with them. however, it is not considered that complicated circuits such as image processing integrated circuit (image processing IC) are connected to the microprocessor to operate them. In the above-described complicated circuits, data processing time usually varies with the contents of an input data.
However, when the circuit is connected to the microprocessor to operate it, the outputting of an outputted data is often required after a predetermined length of time from a time when an inputted data processing is started as a whole. To meet this requirement, a method, where a timer device or the like, to synchronize the microprocessor and the circuit in connection with data processing is provided to synchronize data processing time in accordance with an elapsed time indicated by the timer is considered. However, this is not the best solution considering the complexity of a circuit design which makes the tasks more time consuming.
Another idea to meet this requirement is using memory devices in which output data can be stored to have a microprocessor read the data with the appropriate timing. Even this idea is not satisfactory due to a cost increase.
In this situation, the market requires to develop a simple circuit and appropriate method to be developed in order to solve these problems.